A conventional electric power steering apparatus is constituted of a motor for assisting in mainly driver's steering force, a control device for controlling the motor, a joining device with a reduction mechanism for reducing an output of the motor and transmitting the reduced output to a steering shaft, and sensors and the like for detecting driver's steering force and the like. Note that, the apparatus including a gear portion may also be referred to as an electric power steering apparatus.
Moreover, in recent years, it can be known that an electric power steering apparatus is mounted on a whole category of wheeled vehicles, thereby revealing that, if assist functions stop due to a failure or fault of the electric power steering apparatus, it is close to impossible for the driver to rotate the steering wheel, causing difficulties in running the wheeled vehicle itself. To this end, the need is intensified to continue the assist as much as possible, depending on content of the fault. As one of the measures, an electric power steering apparatus is proposed in which a plurality of motors is provided or stator windings are provided for a motor, and at the same time, a plurality of driving circuits is also included for controlling the plurality of those (for example, refer to Patent Document 1).
In addition, as one measure for miniaturization of an electric power steering apparatus, an electric power steering apparatus of control-device integrated-type is proposed in which a motor and a control device are integrated (for example, refer to Patent Document 2). A conventional apparatus shown in Patent Document 2 is configured to place a control device at an output side of a motor (hereinafter referred to as a “front side”) in a direction in which the axial center of the motor extends (hereinafter referred to as an “axial direction”).